The question asks to identify the endangered fauna from the given options.

Option 1 suggests only Gharial and Leatherback turtle are endangered. Gharials are indeed classified as critically endangered due to threats such as hunting, habitat loss, and fishing. Leatherback turtles, the world`s largest turtles, are also listed as endangered owing to factors like loss of nesting habitat, poaching, and bycatch in fisheries.

Option 2 suggests that only Swamp deer are endangered. However, Swamp deer, also known as Barasingha, is not considered endangered but vulnerable. It used to be endangered, but conservation efforts have helped improve its status.

Option 3 suggests that all three, Gharial, Leatherback turtle, and Swamp deer, are endangered, which is correct despite the Swamp deer being more correctly classified as vulnerable. In common terminology, "endangered" can refer to any species at risk, so this is the most appropriate answer.

Option 4 suggests none of the listed fauna are endangered, which is incorrect given the status of Gharial and Leatherback turtles.